There has been a trend in recent years to provide for the automatic reading of consumption data generated relative to metered commodity usage, such as water meters, electric meters, gas meters, and the like. The meter reading in systems designed to accommodate automatic meter reading typically rely on automated transmission of consumption data. In some systems, this transmission occurs over wires or electro-optical cables. More preferably, the transmission occurs with the radiation of wireless RF energy.
Encoder Receiver Transmitter (ERT) devices are known for use in automatic meter reading systems in which data transmission is accomplished by wireless RF transmission. The assignee of the present invention provides ERT's for virtually every gas and electric meter on the market. For gas meters, ERT installation is typically mounted directly on the gas meter. For electric ERT installation, the ERT module is typically installed inside the glass enclosure in a meter shop environment. The ERT not only collects electric or gas usage data, but also can report such information as meter tampering.
The assignee of the present invention additionally provides an ERT module for use with pit mounted water meters. The ERT module is typically, easily installed in a predrilled hole formed in the meter box lid and coupled via a cable to the water meter mounted in the pit. U.S. Pat. Nos. 5,410,246, 5,442,281, and 5,553,094 (incorporated herein by reference), assigned to the assignee of the present application, are illustrative of the design of ERT modules generally and the design of the radio communication network into which the ERT module is integrated.
Typically, the ERT has a microstrip or partially shielded antenna enclosed within a housing. The housing may be a housing unique to the ERT or the housing may be the housing of the entire meter, such as in the typical electric meter installation. A difficulty with wireless automatic meter reading systems is to ensure that transmissions to and from the meter are reliably received. The transmitter/receiver of the ERT is necessarily a relatively small device. In some installations it is battery powered by a small capacity battery. This places severe limits on the size of the ERT antenna and the power of the ERT transmitter. Accordingly, there is a need in the industry to increase the radio communication range of the ERT modules.
Further, it is understood that any device effective to increase the radio communication range of ERT modules must be potentially applicable to literally millions of installed meters. In order to be acceptable to utility companies, the cost of such a device must be kept to an absolute minimum. Probably more important than the unit cost of the device is the cost of installation of the device in each meter which must be borne by the utility. Accordingly, the most desirable device for increasing the radio communication range of the ERT module is a device that absolutely minimizes the installation cost on ERT modules already in the field.
Gas meters, electric meters, and water meters are typically installed in a number of different locations. They may be inside a building; inside a building in a moist pit; outside a building, but enclosed; and outside a building and fully exposed to the elements. A further requirement of a device for increasing the radio communication range of ERT modules is that it be able to endure the environment in which the ERT module is installed for long periods of time without maintenance attention.